bsd-user:Add AArch64 improvements and signal handling functions

Added get_ucontext_sigreturn function to check processor state ensuring current execution mode is EL0 and no flags
indicating interrupts or exceptions are set.
Updated AArch64 code to use CF directly without reading/writing the entire processor state, improving efficiency.
Changed FP data structures to use Int128 instead of __uint128_t, leveraging QEMU's generic mechanism for referencing this type.

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240707191128.10509-9-itachis@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>

bsd-user/aarch64/signal.c

@@ -21,7 +21,7 @@
 #include "qemu.h"
 
 /*
- * Compare to sendsig() in sys/arm64/arm64/machdep.c
+ * Compare to sendsig() in sys/arm64/arm64/exec_machdep.c
  * Assumes that target stack frame memory is locked.
  */
 abi_long set_sigtramp_args(CPUARMState *regs, int sig,
@@ -117,3 +117,21 @@ abi_long set_mcontext(CPUARMState *regs, target_mcontext_t *mcp, int srflag)
 
     return err;
 }
+
+/* Compare to sys_sigreturn() in  arm64/arm64/machdep.c */
+abi_long get_ucontext_sigreturn(CPUARMState *regs, abi_ulong target_sf,
+                                abi_ulong *target_uc)
+{
+    uint32_t pstate = pstate_read(regs);
+
+    *target_uc = 0;
+
+    if ((pstate & PSTATE_M) != PSTATE_MODE_EL0t  ||
+        (pstate & (PSTATE_F | PSTATE_I | PSTATE_A | PSTATE_D)) != 0) {
+        return -TARGET_EINVAL;
+    }
+
+    *target_uc = target_sf;
+
+    return 0;
+}

bsd-user/aarch64/target_arch_cpu.h

@@ -48,7 +48,6 @@ static inline void target_cpu_loop(CPUARMState *env)
     CPUState *cs = env_cpu(env);
     int trapnr, ec, fsc, si_code, si_signo;
     uint64_t code, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8;
-    uint32_t pstate;
     abi_long ret;
 
     for (;;) {
@@ -88,18 +87,16 @@ static inline void target_cpu_loop(CPUARMState *env)
              * The carry bit is cleared for no error; set for error.
              * See arm64/arm64/vm_machdep.c cpu_set_syscall_retval()
              */
-            pstate = pstate_read(env);
             if (ret >= 0) {
-                pstate &= ~PSTATE_C;
+                env->CF = 0;
                 env->xregs[0] = ret;
             } else if (ret == -TARGET_ERESTART) {
                 env->pc -= 4;
                 break;
             } else if (ret != -TARGET_EJUSTRETURN) {
-                pstate |= PSTATE_C;
+                env->CF = 1;
                 env->xregs[0] = -ret;
             }
-            pstate_write(env, pstate);
             break;
 
         case EXCP_INTERRUPT:

bsd-user/aarch64/target_arch_reg.h

@@ -31,7 +31,7 @@ typedef struct target_reg {
 } target_reg_t;
 
 typedef struct target_fpreg {
-    __uint128_t     fp_q[32];
+    Int128          fp_q[32];
     uint32_t        fp_sr;
     uint32_t        fp_cr;
 } target_fpreg_t;

bsd-user/aarch64/target_arch_signal.h

@@ -49,7 +49,7 @@ struct target_gpregs {
 };
 
 struct target_fpregs {
-    __uint128_t fp_q[32];
+    Int128      fp_q[32];
     uint32_t    fp_sr;
     uint32_t    fp_cr;
     uint32_t    fp_flags;

bsd-user/qemu.h

@@ -17,6 +17,9 @@
 #ifndef QEMU_H
 #define QEMU_H
 
+#include <sys/param.h>
+
+#include "qemu/int128.h"
 #include "cpu.h"
 #include "qemu/units.h"
 #include "exec/cpu_ldst.h"